Router connections through switching networks using virtual circuits

Abstract

A router routes data packets between local area networks. Upon receiving data packets, the router detects a destination for the data packets. Router processing circuitry within the router searches a routing table to obtain a routing table entry for the destination. When the routing table entry indicates that a virtual circuit is to be used to pass the data packets to a next hop router, the router obtains a phone number for the next hop router. The router then uses the phone number to establish connection with the next hop router over a switching network. The router then transfers the data packets to the next hop router over the established connection.

We claim: 
     
       1. A router comprising: router processing circuitry for routing data transferred between local area networks;   a routing table, accessed by the processing circuitry, the routing table including a plurality of routing table entries, each routing table entry including an address for a next hop router, and a reference to a cost value for a route represented by the table entry;     a virtual connection map table accessed by the routing processing circuitry, the virtual connection map table having a plurality of virtual connection map table entries, each virtual connection map table entry having a phone number for a next hop router, wherein for each virtual connection, a routing table entry includes a reference to a virtual connection map table entry;   a plurality of virtual connection circuits;   a virtual connection map queue onto which the router places data packets to be transferred through the virtual connection circuits; and,   circuit allocation routines, coupled to the plurality of virtual connection circuits and to the virtual connection map queue, for selecting a virtual connection circuit from the plurality of virtual connection circuits over which to transfer data packets from the virtual connection map queue.   
     
     
       2. A router used to route data packets between local area networks, the router comprising: a routing table;   searching means, connected to the routing table, for searching the routing table to obtain a routing table entry for a destination for the data packets, the searching means including selecting means for selecting a routing table entry with a lowest associated cost value when the routing table contains more than one routing table entry for the destination; and,   virtual circuit means for passing the data packets to a next hop router when the routing table entry indicates that a virtual circuit is to be used to, virtual circuit means including virtual circuit mapping means for obtaining a phone number for the next hop router,   virtual circuit means for establishing connection with the next hop router over a switching network, and   transferring means for transferring the data packets to the next hop router;     wherein the virtual circuit means includes a plurality of virtual connection circuits,   a virtual connection map queue onto which the router places data packets to be transferred through the virtual connection circuits, and   circuit allocation routines, coupled to the plurality of virtual connection circuits and to the virtual connection map queue, for selecting a virtual connection circuit from the plurality of virtual connection circuits over which to transfer data packets from the virtual connection map queue.     
     
     
       3. A router as in claim 2 wherein each virtual connection circuit is connected to a switching network through an adapter/modem. 
     
     
       4. A router as in claim 3 wherein the switching network is an Integrated Services Digital Network.